Blind fastener

ABSTRACT

A blind fastener device for fastening workpieces, including a sleeve, an expander having a locking section and an expansion section, and a separate and distinct tensioning section configured to mechanically cooperate with the expander. One end of the tensioning section is configured as a tensioning section gripping region, which may be formed as the head of a bolt. A portion of the tensioning section passes through the sleeve to cooperate with the expander so that relative rotation of the tensioning section and the expander draws the expander distal end toward the sleeve proximal end and ultimately deforming a portion of the sleeve distal end to a locked state. The sleeve may be configured as a multi-section sleeve having a sleeve retainer to locate the sections in a predetermined relationship.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/622,023, filed on Feb. 13, 2015, which claims the benefit of U.S.provisional patent application Ser. No. 62/039,939, filed on Aug. 21,2014, all of which are incorporated by reference as if completelywritten herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to blind fasteners which arecapable of fastening structures which produce shear loading across theblind fastener; particularly structures comprised of structural plates,tubes, and other shapes that are commonly used in towers, poles, storagetanks, and other structures.

BACKGROUND OF THE INVENTION

Blind fasteners have generally incorporated a sleeve that expands andbends during installation often exposing sharp edges of the sleeve, asseen in U.S. Pat. No. 6,234,734. Exposing such sharp edges in an emptyhollow structure may be acceptable, however exposed sharp edges in astructure filled with wires and/or cables can be disastrous,particularly when more wires and/or cables are pulled through thestructure after the sharp edges have been exposed.

In addition to sharp edges found on the expanding sleeves of prior artblind fasteners, the blind fasteners in the prior art often requirespreassembly and special tools to install them on various workstructures.Take for instance a technician that is assembling a tower structuresuspended high above the ground. In this scenario, the technician mustassemble the blind fastener in a certain order and use multiple tools toput the blind fastener into an engaged state. In this scenario thetechnician must be careful not to drop any of the blind fastenerscomponents, or tools, out of inconvenience of recovering the droppedcomponents and the safety risk to those that may below him.Additionally, the mere fact that the technician needs multiplespecialized tools means that they have to carry additional weight whileperforming their work. Additionally, the extra tools required alsoincreases the inconvenience and hazards of dropped tools.

SUMMARY OF THE INVENTION

A blind fastener to secure at least two workpieces enables a significantadvance in the state of the art and greatly improves wire and cableprotection, job site safety and simplifies blind fastener installation.A blind fastener device for fastening at least two workpieces, includinga sleeve, an expander having a tensioning section, a locking section,and an expansion section, and a nut. A portion of the expander passesthrough the sleeve to cooperate with the nut so that relative rotationof the expander and nut draws the expander's distal end toward thesleeve's proximal end thereby drawing a portion of the expansion sectionof the expander into a structural region located on the sleeve andexpanding at least a portion of the sleeve's structural region, anddrawing a portion of the locking section past the sleeve's distal endtoward the sleeve's proximal end and deforming at least a portion of thesleeve's distal end to a locked state. The sleeve may be configured as amulti-section sleeve having a sleeve retainer to locate the sections ina predetermined relationship.

BRIEF DESCRIPTION OF THE DRAWINGS

Without limiting the scope of the present invention as claimed below andreferring now to the drawings and figures:

FIG. 1 is an embodiment of an exploded view of a blind fasteneraccording to the present invention;

FIG. 2 is a cross-sectional exploded view of an embodiment of a blindfastener embodiment;

FIG. 3 is a plan view of an embodiment of a pre-insertion pre-actuationblind fastener with the shroud and workpieces shown in section forclarity;

FIG. 4 is a plan view of an embodiment of a post-insertion pre-actuationblind fastener with the shroud and workpieces shown in section forclarity;

FIG. 5 is a plan view of an embodiment of a post-insertion pre-actuationblind fastener with the shroud and workpieces shown in section forclarity;

FIG. 6 is a cross-sectional view of an embodiment of a post-insertionpre-actuation blind fastener;

FIG. 7 is a partial cross-sectional view of an embodiment of apost-insertion pre-actuated blind fastener;

FIG. 8 is a cross-sectional view of an embodiment of a post-insertionpre-actuated blind fastener;

FIG. 9 is a plan view of an embodiment of a post-insertionpartial-actuated blind fastener with the shroud and workpieces shown insection for clarity;

FIG. 10 is a cross-sectional view of an embodiment of a post-insertionpartial-actuated blind fastener;

FIG. 11 is a partial cross-sectional view of an embodiment of apost-insertion partial-actuated blind fastener;

FIG. 12 is a cross-sectional view of an embodiment of a post-insertionpartial-actuated blind fastener;

FIG. 13 is a plan view of an embodiment of a post-insertionfully-actuated blind fastener with the shroud and workpieces shown insection for clarity;

FIG. 14 is a cross-sectional view of an embodiment of a post-insertionfully-actuated blind fastener;

FIG. 15 is a partial cross-sectional view of an embodiment of apost-insertion fully-actuated blind fastener;

FIG. 16 is a cross-sectional view of an embodiment of a post-insertionfully-actuated blind fastener;

FIG. 17 is a plan view of an expander embodiment;

FIG. 18 is a plan view of another expander embodiment;

FIG. 19 is an exploded plan view of a sleeve, retainer and shroudassembly embodiment;

FIG. 20 is a cross-sectional exploded plan view of a sleeve, retainerand shroud assembly embodiment;

FIG. 21 is another embodiment of an exploded plan view of a sleeve,retainer and shroud assembly;

FIG. 22 is another embodiment of a cross-sectional exploded plan view ofa sleeve, retainer and shroud assembly;

FIG. 23 is another embodiment of an exploded view of a blind fastener;

FIG. 24 is another embodiment of a cross-sectional exploded view of ablind fastener;

FIG. 25 is a plan view of another expander embodiment;

FIG. 26 is another embodiment of a plan view of an expander;

FIG. 27 is another embodiment of a plan view of a sleeve;

FIG. 28 is another embodiment of a cross-sectional plan view of asleeve;

FIG. 29 is another embodiment of a cross-sectional view of a blindfastener;

FIG. 30 is another embodiment of a cross-sectional view of apost-insertion pre-actuation blind fastener;

FIG. 31 is another embodiment of a cross-sectional view of apost-insertion fully-actuated blind fastener;

FIG. 32 is another embodiment of a cross-sectional view of apost-insertion pre-actuation blind fastener;

FIG. 33 is another embodiment of a cross-sectional view of apost-insertion fully-actuated blind fastener;

FIG. 34 is another embodiment of a cross-sectional view of apost-insertion pre-actuation blind fastener;

FIG. 35 is another embodiment of a cross-sectional view of apost-insertion fully-actuated blind fastener;

FIG. 36 is a plan view of another embodiment of a sleeve retainer andpre-inserted sleeve;

FIG. 37 is a plan view of another embodiment of a sleeve retainer and apartially inserted sleeve;

FIG. 38 is a plan view of another embodiment of a sleeve retainer and afully inserted sleeve;

FIG. 39 is a plan view of another embodiment of a sleeve retainerundergoing contraction and a fully inserted sleeve;

FIG. 40 is a plan view of another embodiment of a fully contractedsleeve retainer and a fully inserted sleeve;

FIG. 41 is a cross-sectional and magnified view of another embodiment ofa fully contracted sleeve retainer and a fully inserted sleeve;

FIG. 42 is another cross-sectional view of another embodiment of a fullycontracted sleeve retainer and a fully inserted sleeve;

FIG. 43 is a plan view of another sleeve embodiment having a channel;

FIG. 44 is a cross-sectional and magnified view of another embodiment ofa sleeve having channels;

FIG. 45 is a plan view of another sleeve embodiment having channels;

FIG. 46 is a plan view of another sleeve embodiment having channels;

FIG. 47 is a partial cross-sectional view of another sleeve embodiment;

FIG. 48 is a partial cross-sectional view of another embodiment of asleeve having a sleeve retainer;

FIG. 49 is a plan view of another sleeve embodiment with bonded sleevesections;

FIG. 50 is a cross-sectional view of another embodiment of a sleeve withbonded sleeve sections;

FIG. 51 is a partial cross-sectional view of an embodiment of apost-insertion fully-actuated blind fastener;

FIG. 52 is a partial cross-sectional view of an embodiment of apost-insertion un-actuated blind fastener;

FIG. 53 is a partial cross-sectional view of an embodiment of apost-insertion fully-actuated blind fastener;

FIG. 54 is a partial cross-sectional view of an embodiment of apost-insertion fully-actuated blind fastener;

FIG. 55 is a cross-sectional and magnified view of another embodiment ofa sleeve having a single channel;

FIG. 56 is a cross-sectional view of another embodiment of a sleeve;

FIG. 57 is a cross-sectional view of an embodiment of a post-insertionpre-actuated blind fastener;

FIG. 58 is a cross-sectional view of an embodiment of a post-insertionpartial-actuated blind fastener; and

FIG. 59 is a cross-sectional view of an embodiment of a post-insertionfully-actuated blind fastener.

These illustrations are provided to assist in the understanding of theexemplary embodiments of a blind fastener as described in more detailbelow and should not be construed as unduly limiting the specification.In particular, the relative spacing, positioning, sizing and dimensionsof the various elements illustrated in the drawings may not be drawn toscale and may have been exaggerated, reduced or otherwise modified forthe purpose of improved clarity. Those of ordinary skill in the art willalso appreciate that a range of alternative configurations have beenomitted simply to improve the clarity and reduce the number of drawings.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to FIGS. 1 and 2, show an exploded view of anembodiment of a blind fastener. In this particular embodiment the maincomponents of the blind fastener may include a sleeve (100), a sleeveretainer (200), an expander (400), a nut (500), and optionally a shroud(300) and/or a washer system (600).

The sleeve (100) will first be disclosed in detail. The sleeve (100)serves the role of expanding radially in order to fill openings locatedin workpieces being fastened together. The expanding sleeve (100) servesto eliminate any movement in the workpieces in relation to one anotherdue to loose fitting fasteners; the sleeve (100) reduces the likelihoodof fasteners failing due to shear loading on the fastener; and sleeve(100) facilitates the blind fastener locking in place. Now withreference to FIGS. 19 and 20, the sleeve (100) has a sleeve proximal end(120), and a sleeve distal end (130). The sleeve (100) has a sleevelength (155) which is defined as the distance from the sleeve proximalend (120) to the sleeve distal end (130). Furthermore, the sleeve (100)has a sleeve outer diameter (140) that is adjacent the walls of a firstworkpiece opening (720), located in a first workpiece (700) having afirst workpiece opening diameter (722) and a first workpiece thickness(710), and the walls of a second workpiece opening (820), located in asecond workpiece (800) having a second workpiece opening diameter (822)and a second workpiece thickness (810), when the blind fastener isinstalled, as seen in FIGS. 3, 13 and 15. In some embodiments, thesleeve (100) may be composed of two or more distinct segments, or two ormore segments that are formed when the sleeve (100) splits apart, aswill be disclosed later in great detail. For instance, the embodimentsof in FIGS. 6, 8, 10, 12, 14, 16, 34 and 35 have a first sleeve section(101), a second sleeve section (102), a third sleeve section (103), anda forth sleeve section (104), however the embodiment of FIG. 56illustrates a single sleeve section embodiment, while FIG. 30illustrates a two sleeve section embodiment, and FIG. 32 illustrates athree sleeve section embodiment.

As seen in FIGS. 43-46, embodiments of the sleeve (100) may incorporateone or more frangible sections that break apart during use to createdistinct sleeve sections. The sleeve (100) may have at least onelongitudinal sleeve channel (110) that provides a fracturable area onthe sleeve (100). Each longitudinal sleeve channel (110) has a sleevechannel width (111) and sleeve channel length (112), as seen in FIGS.43-44, that may be created by, but not limited to, milling, stamping,casting, and press forming during the creation of the sleeve (100). FIG.43 illustrates an embodiment of sleeve (100) having at least onelongitudinal sleeve channel (110) with the sleeve channel length (112)equal to 100% of the sleeve length (155), thereby allowing the sleeve(100) to fracture into full sleeve (100) sections. FIG. 44 is a crosssectional view of a sleeve (100) designed to fracture into foursections, having a sleeve first channel (115), a sleeve second channel(116), a sleeve third channel (117), and a sleeve forth channel (118).Depending on the application, variations in the first workpiecethickness (710) and the second workpiece thickness (810) may induce aneed for other embodiments of fracturable sleeves (100). FIG. 55 is across sectional view of a sleeve (100) designed to fracture having asingle sleeve first channel (115), however it may be formed with twochannels, three channels, four channels, five channels, or even six, ormore, channels.

One embodiment of sleeve (100), as shown in FIG. 45, incorporates one ormore sleeve channels (110) that do not extend the entire length of thesleeve (100). One benefit of such an embodiment is that the additionalload must be applied to the blind fastener to split the sleeve (100)into separate sections ensuring a tighter joint. One, or more, partialsleeve channels (110) may be located on the sleeve proximal end (120),having a sleeve proximal end channel length (113), and/or one, or more,partial sleeve channels (110) may be located on the sleeve distal end(130), having a sleeve distal end channel length (114). The partialsleeve channels (110) may align as seen in FIG. 45, or they be offset asseen in FIG. 46. In one embodiment at least two partial sleeve channels(110) extend from the sleeve proximal end (120) toward the sleeve distalend (130). This embodiment ensures that the sleeve (100) splits into atleast two distinct pieces. In another embodiment at least two partialsleeve channels (110) extend from the sleeve distal end (130) toward thesleeve proximal end (120). In yet a further embodiment at least twodistally extending partial channels align with at least two proximallyextending partial channels, as seen in FIG. 45. In an even furtherembodiment at least three partial sleeve channels (110) extend from thesleeve proximal end (120) toward the sleeve distal end (130). Thisembodiment ensures that the sleeve (100) splits into at least threedistinct pieces; and in another embodiment at least three partial sleevechannels (110) extend from the sleeve distal end (130) toward the sleeveproximal end (120). In yet a further embodiment at least three distallyextending partial channels align with at least three proximallyextending partial channels. In yet an even further embodiment at leastfour partial sleeve channels (110) extend from the sleeve proximal end(120) toward the sleeve distal end (130), similar to the section of FIG.44. This embodiment ensures that the sleeve (100) splits into at leastfour distinct pieces; and in another embodiment at least four partialsleeve channels (110) extend from the sleeve distal end (130) toward thesleeve proximal end (120). In yet a further embodiment at least fourdistally extending partial channels align with at least four proximallyextending partial channels.

In one embodiment the sleeve proximal end channel length (113) is lessthan 95% of the sleeve length (155), while in a further embodiment, thesleeve proximal end channel length (113) is 15-80% of the sleeve length(155), and in an even further embodiment, the sleeve proximal endchannel length (113) is 30-60% of the sleeve length (155), while in aneven further embodiment the sleeve proximal end channel length (113) isless than 50% of the sleeve length (155). Likewise, in anotherembodiment the sleeve distal end channel length (114) is less than 95%of the sleeve length (155), while in a further embodiment, the sleevedistal end channel length (114) is 15-80% of the sleeve length (155),and in an even further embodiment, the sleeve distal end channel length(114) is 30-60% of the sleeve length (155), while in an even furtherembodiment the sleeve distal end channel length (114) is less than 50%of the sleeve length (155). In some applications it may be desirable forthe sleeve (100) to include partial sleeve channels (110) located onboth the sleeve proximal end (120) and sleeve distal end (130), having asleeve proximal end channel length (113) and a sleeve distal end channellength (114). In one such embodiment preferential loading is achievedwhen there is a separation distance between the ends of the channelsthat is 1-20% of the sleeve length (155), while in a further embodimentthe separation distance is 5-10% of the sleeve length (155), which isenough to require additional fastener loading to split the sleeve (100)into sections.

The depth of any of the disclosed sleeve channels (110), full length orpartial length, may also be used to control the fastener loading neededto split the sleeve (100) into sections. The depth, seen in FIG. 44, ispreferably at least 50% of the maximum structural region wall thickness(172), seen in FIG. 20 and later described in detail. In a furtherembodiment the depth is 60-95% of the maximum structural region wallthickness (172), while in an even further embodiment the depth is 75-95%of the maximum structural region wall thickness (172).

In another embodiment, the sleeve (100) may have separate sections thatare bonded together by a sleeve bonding agent (105), as seen in FIGS. 49and 50. The sleeve bonding agent (105) bonds the individual sleevesections into a fracturable sleeve (100) unit which breaks apart intoindividual sleeve (100) sections when exposed to a predetermined load.The sleeve bonding agent (105) may include, but is not limited to, adirectly applied adhesive or polymer applied between the sections asseen in FIGS. 49-50, an adhesive or polymer in which the sleeve (100) isdipped thereby covering a portion, or all, of the sleeve (100), and aninjection cast polymer inner sleeve (100) surface, outer sleeve (100)surface or a completely embedded sleeve (100). Further, the sleevebonding agent (105) may be soldering or brazing alloy, or even a weldmaterial produced during a continuous, or a spot, welding process. Thus,in some embodiments the sleeve bonding agent (105) does not extend thefull length of the individual sleeve sections.

In another embodiment, the sleeve (100) may have pre-separated distinctsections that are held in place by one or more sleeve retainers (200),as seen in FIGS. 1-15, 19-20, 23-24, and 48, and in some embodiments ashroud (300). In one embodiment the sleeve (100) includes at least twodistinct sections (101, 102), as seen in FIGS. 30-31, while in anotherembodiment the sleeve (100) includes at least three distinct sections(101, 102, 103), as seen in FIGS. 32-33, and in an even furtherembodiment includes at least four distinct sections (101, 102, 103,104), as seen in FIGS. 34-35. The segmentation of the sleeve (100)allows the sleeve outer diameter (140) to expand when the blind fasteneris actuated, as seen in FIGS. 31, 33, and 35, and provides edges of thedistinct sections that bite into the workpieces (700, 800). The sleeve(100) has a sleeve inner diameter (150), seen in FIG. 6, forming a borein which the expander (400) passes through.

As seen in FIGS. 19 and 20, in one embodiment the sleeve (100) has aretainer engagement region (160) having a retainer engagement regionwall thickness (162), a retainer engagement length (164) and a retainerengagement region diameter (168). While the embodiment of FIG. 20illustrates the sleeve retainer (200) located at the sleeve proximal end(120), it may be located anywhere along the length of the sleeve (100,as seen near the middle of the sleeve (100) in FIG. 21 and at the sleevedistal end (130) in FIG. 48.

In some embodiments the sleeve (100) includes at least one retainerengagement region ledge (166), as illustrated in FIGS. 20 and 47. Theengagement region ledge (166) provides a surface for the sleeve retainer(200) to abut and helps provide a smooth transition from the sleeveretainer (200) and sleeve (100). In such ledge embodiments the retainerengagement region wall thickness (162) is preferably at least 20% of amaximum structural region wall thickness (172), while in a furtherembodiment the retainer engagement region wall thickness (162) is 30-95%of the maximum structural region wall thickness (172), and in an evenfurther embodiment the retainer engagement region wall thickness (162)is at least 50% of the maximum structural region wall thickness (172). Astill further embodiment has a retainer engagement region wall thickness(162) of at least 65% of the maximum structural region wall thickness(172). The minimum retainer engagement region wall thickness (162)ensures that the retainer engagement region (160) will not crushlongitudinally when subjected to severe loading. Additionally theretainer engagement region (160) may have a retainer engagement regionwall thickness (162) such that when the retainer (200) is attached tothe retainer engagement region (160), the sum of the retainer engagementregion wall thickness (162) and the retainer thickness, which is halfthe distance between the sleeve engagement section outer diameter (216)and the sleeve engagement section inner diameter (214) seen in FIG. 20,is not more than the structural region wall thickness (172), therebyensuring passage through a tight opening (720, 820) in the workpieces(700, 800).

Furthermore, in one embodiment the sleeve (100) has a retainerengagement region (160) located on the sleeve proximal end (120)allowing the sleeve retainer (200) to be affixed to the sleeve (100), asseen in FIG. 19. In a further embodiment, the retainer engagement region(160) is located in an area located between the sleeve proximal end(120) and the sleeve distal end (130), as seen in FIGS. 21 and 22. Inanother embodiment, the retainer engagement region (160) is located onthe sleeve distal end (130) as seen in FIG. 47, which also serves tocover the sleeve distal end (130) as it flairs outward thereby providingmany of the benefits discussed later herein with respect to the shroud(300) embodiment. In yet another embodiment, the retainer engagementregion (160) includes the entire sleeve length (155), as seen in FIG. 36and described later in more detail

Additionally, the sleeve (100) has a structural region (170) with astructural region length (174) and a structural region wall thicknessdefined by the sleeve outer diameter (140) and the sleeve inner diameter(150), as illustrated by FIGS. 19 and 20. The structural region (170)has a structural region length (174) sufficiently long enough to engagethe first workpiece (700) and second workpiece (800) when the blindfastener is placed through the overlapping first workpiece opening (720)and second workpiece opening (820) as illustrated in FIGS. 3 and 4. Inorder to accommodate a wide variety of workpiece thicknesses andconfigurations, the structural region length (174) is preferably atleast 35% greater than an expansion section length (448), seen in FIG.17 and discussed later in detail. While in another embodiment thestructural region length (174) is preferably at least 50% greater thanan expansion section length (448), and in yet a further embodiment thestructural region length (174) is 50-95% greater than an expansionsection length (448). Furthermore, when the blind fastener is in a fullyactuated locked state, the sleeve structural region (170) and theexpander (400) substantially fill the opening in the workpieces andimpart a radial load on the workpiece openings, while resisting shearforces at a workpiece interface (900) located where the first workpieceopening (720) and second workpiece opening (820) abut, as seen in FIGS.3, 4, 13 and 15. The structural region (170) of the sleeve (100) is thatportion intended to carry the load at the shear plane of the workpieceinterface (900), and includes the adjacent portions of the sleeve (100)having a sleeve outer diameter (140) within 5% of the maximum sleeveouter diameter (140), but this does not require the structural region(170) to have a perfectly smooth outer surface. For instance, the outersurface of the structural region (170) may have surface texturing orstippling to increase the grip as the outer surface comes in contactwith the workpieces (700, 800); further, the outer surface of thestructural region (170) may have channels in the outer surface, whichmay produce limited regions in which the sleeve outer diameter (140) isnot within 5% of the maximum sleeve outer diameter (140) provided (a)the total volume of such channels is less than 25% of the volume of thestructural region (170), and (b) in a series of five equally spacedtransverse cross-sections through the structural region (170) at leastthree of the five transverse cross-sections have at least 50% of thecross-sectional perimeter is within 5% of the maximum sleeve outerdiameter (140), thereby allowing limited longitudinal channels, as wellas limited transverse channels, within the structural region (170).

In one embodiment the structural region (170) has a structural regionwall thickness (172), as seen in FIGS. 20 and 22. Further, the retainerengagement region wall thickness (162) of the retainer engagement region(160), as seen in FIGS. 19 and 20, has a minimum retainer engagementregion wall thickness (162) that is at least 25% of the maximumstructural region wall thickness (172) to ensure the retainer engagementregion (160) does not compress longitudinally as the expander (400) isdrawn into the structural region (170) of the sleeve (100). In anotherembodiment the sleeve (100) may also have a shroud engagement region(190) on which the shroud (300) may attach, as shown in FIGS. 19 and 20.The shroud engagement region (190) has a shroud engagement region length(192) that is sufficiently long enough to allow the shroud (300) toremain attached during the actuation and locking of the blind fastener.In reference to the shroud (300), the shroud has a proximal end (310), ashroud distal end (320) and a shroud thickness (330), as shown in FIGS.1 and 20. The shroud (300) may be composed of an elastic material, ormay have a hard protective cap with an elastic skirt on the shroudproximal end (310) that attaches to the shroud engagement region (190).Furthermore, the shroud (300) cooperates with sleeve shroud engagementregion (190) and encloses at least a portion of the expander (400) and aportion of the sleeve (100), as seen in FIG. 5; while in a furtherembodiment the shroud (300) encloses the sleeve distal end (130) and theexpander distal end (420) in the initial state, the expanded state, andthe locked state; and in an even further embodiment the shroud (300) hasa shroud proximal end (310), a shroud distal end (320), and a shroudthickness (330), whereby the shroud proximal end (310) is attached tothe sleeve (100) and the shroud distal end (320) totally encloses andseals the sleeve distal end (130). In many embodiments at least aportion of the shroud (300) is elastic and applies a compressive forceon to the sleeve (10).

The shroud (300) serves an important function of protecting cables frombeing damaged from the exposed surfaces of a blind fastener, however aspreviously disclosed this protective function may also be achieved viathe sleeve retainer (200) when positioned at the sleeve distal end (130)as shown in FIG. 48. The shroud engagement region (190) may have ashroud engagement region ledge (194) against which the shroud proximalend (310) abuts as seen in FIGS. 19 and 20. Additionally the shroudengagement region (190) may have a shroud engagement region wallthickness (196) such that when the shroud (300) is attached to theshroud engagement region (190), the sum of the shroud engagement regionwall thickness (196) and the shroud thickness (330) is not more than thestructural region wall thickness (172). Furthermore, in anotherembodiment the shroud engagement region wall thickness (196) is at least25% of the maximum structural region wall thickness (172) to ensure thatthe shroud engagement region (190) does not compress longitudinally asthe expander (400) is drawn into the structural region (170) of thesleeve (100). In a further embodiment the shroud engagement region wallthickness (196) is 30-95% of the maximum structural region wallthickness (172), and in an even further embodiment the shroud engagementregion wall thickness (196) is at least 50% of the maximum structuralregion wall thickness (172). One particular embodiment has a minimumshroud engagement region wall thickness (196) that is 25-50% of themaximum structural region wall thickness (172). A still furtherembodiment has a shroud engagement region wall thickness (196) of atleast 65% of the maximum structural region wall thickness (172). In someembodiments the sleeve (100) includes a shroud engagement region (190)having a shroud engagement region length (192) that is at least 10% ofthe structural region length (174), and the shroud (300) cooperates withthe shroud engagement region (190). In a further embodiment the shroudengagement region length (192) is 10-50% of the structural region length(174). The shroud engagement region (190) may be a circumferentialrecess in the exterior surface of the sleeve (100) thereby creating atleast one shroud engagement region ledge (194) to shield at least oneedge of the shroud (300).

The sleeve (100) may include a sleeve throat (180) having a throatlength (182), a throat angle (184), and a throat wall thickness (186),as illustrated in FIG. 20. The throat wall thickness (186) tapers as itapproaches the sleeve distal end (130), as illustrated in FIG. 20. Inone embodiment, the mid-point of the sleeve throat (180) has a throatwall thickness (186) of not less than 25% of the maximum structuralregion wall thickness (172). In another embodiment, the mid-point of thesleeve throat (180) has throat wall thickness (186) of not more than 75%of the maximum structural region wall thickness (172), while in yet afurther embodiment, the mid-point of the sleeve throat (180) has throatwall thickness (186) that is 25-75% of the maximum structural regionwall thickness (172). The throat wall thickness (186) ensure that theshroud engagement region (190) can easily enter the sleeve throat (180)and begin the deformation of the sleeve (100), which is completed by thelocking section (430), while not compressing longitudinally as theexpander (400) is drawn into the sleeve (100).

In one embodiment the sleeve throat length (182) is at least 25% of thelength of the shroud engagement region (190), or the retainer engagementregion length (164) when the sleeve retainer (200) when positioned atthe sleeve distal end (130) as shown in FIG. 48. In another embodiment,the sleeve throat length (182) does not exceed 75% of the length of theshroud engagement region (190) or the retainer engagement region length(164). The sleeve throat length (182) and tapering throat wall thickness(186) forms a throat angle (184) which acts as a ramp within the sleevethroat (180) that helps ensure proper alignment and ingress of theexpander (400) as it is drawn into the sleeve (100), as seen in FIG. 7.Furthermore, in one embodiment the throat angle (184) is 5-50 degrees,while in a further embodiment the throat angle (184) is 10-45 degrees,and in an even further embodiment the throat angle (184) is 15-30degrees. The throat length (182) and throat angle (184) ensure that theshroud engagement region (190) can easily enter the sleeve throat (180)and begin the radial expansion and deformation of the sleeve (100) viathe locking section (430), while not compressing longitudinally as theexpander (400) is drawn into the sleeve (100).

The sleeve retainer (200) may be elastic in nature, contractible innature, or non-elastic in nature, but applied with a preload, and has asleeve engagement section (210) that cooperates with the retainerengagement region (160) to maintain the sleeve (100) in an initialstate. As seen in FIGS. 19, 20 and 42, the sleeve engagement section(210) of the sleeve retainer (200) has a sleeve engagement sectionlength (212), a sleeve engagement section inner diameter (214), a sleeveengagement section outer diameter (216), and a retainer thickness, whichis one-half of the difference between the sleeve engagement sectionouter diameter (216) and the sleeve engagement section inner diameter(214). In one embodiment, the sleeve engagement section outer diameter(216) is not more than the sleeve outer diameter (140) when the sleeveretainer (200) is attached to the retainer engagement region (160). Inanother embodiment, the sleeve engagement section outer diameter (216)is 1-15% larger than the sleeve outer diameter (140) when the sleeveretainer (200) is attached to the retainer engagement region (160),thereby providing a consistent outer surface of the blind fastener thatcan easily enter workpiece openings that are extremely tight withoutsnagging. In yet another embodiment, the sleeve engagement section outerdiameter (216) is less than the sleeve outer diameter (140) when thesleeve retainer (200) is attached to the retainer engagement region(160). Additionally, in one embodiment the sleeve engagement sectionlength (212) is approximately the same as the retainer engagement regionlength (164) in order to prevent overlapping of the sleeve engagementsection (210) when the sleeve retainer (200) is affixed to the retainerengagement region (160) of the sleeve (100), while in a furtherembodiment the sleeve engagement section length (212) is less than theretainer engagement region length (164) in order to prevent overlappingof the sleeve engagement section (210) when the sleeve retainer (200) isaffixed to the retainer engagement region (160) of the sleeve (100). Thesleeve engagement section length (212) may be at least 10% of thestructural region length (174), while in a further embodiment the sleeveengagement section length (212) is 10-50% of the structural regionlength (174), while in an even further embodiment the sleeve engagementsection length (212) is a circumferential recess in the exterior surfaceof the sleeve (100) thereby creating at least one retainer engagementregion ledge (166) to shield at least one edge of the sleeve retainer(200). The retainer engagement region (160) has a retainer engagementregion wall thickness (162), and the structural region (170) has astructural region wall thickness (172), whereby in one embodiment theminimum retainer engagement region wall thickness (162) is at least 25%of the maximum structural region wall thickness (172) to ensure theretainer engagement region (160) does not compress longitudinally as theexpander (400) is drawn into the sleeve (100). Even further, the minimumretainer engagement region wall thickness (162) is 25-50% of the maximumstructural region wall thickness (172) provides the necessary strength.These relationships provide a sleeve retainer (200) to sleeve (100)connection that is strong enough to withstand the forces encountered asthe sleeve (100) is installed and radially expanded.

In another embodiment seen in FIG. 48, the sleeve retainer (200) may belocated on, and overlap, the sleeve distal end (130) thereby forming asleeve retainer protrusion (230). As previously mentioned, in thisembodiment the sleeve retainer (200) provides the benefits previouslydescribed as being associated with the shroud (300) embodiment. Thesleeve retainer protrusion has a sleeve retainer protrusion length (232)and a sleeve retainer protrusion width (234), as seen in FIG. 48. Theretainer protrusion width (234) may have the same thickness as the fullycontracted sleeve retainer (200). However, in one embodiment theretainer protrusion width (234) is greater than the height of theretainer engagement region ledge (166) and wraps around a portion of thesleeve distal end (130) further ensuring that the sleeve retainer (200)remains in place as the sleeve distal end (130) flares outward as theexpander (400) is drawn into the sleeve (100) as seen in FIG. 15. Takingthis even further, in the embodiment of FIG. 48 the retainer protrusionwidth (234) is equal to the height of the retainer engagement regionledge (166) and the throat wall thickness (186) at the sleeve distal end(130). Further, in another embodiment the sleeve retainer (200) has asleeve engagement section length (212) that is at least as great as thesleeve throat length (182), thereby further reducing the likelihood thatthe sleeve retainer (200) moves out of position as the sleeve distal end(130) flares outward as the expander (400) is drawn into the sleeve(100). In an even further embodiment the sleeve engagement sectionlength (212) is at least 50% greater than the sleeve throat length(182), and is at least 75% greater than the sleeve throat length (182)in another embodiment, while in a further embodiment the sleeve retainerprotrusion length (232) is at least 5% of the retainer engagement regionlength (164). The retainer protrusion width (234) may have a thicknessthat is at least 15-30% greater than the sleeve retainer (200) sleeveengagement section outer diameter (216) minus the sleeve engagementsection inner diameter (214). The sleeve retainer protrusion (230)provides the benefit of aiding in the alignment and installation of theblind protective fastener, and also helps shield wires, cables and otherimportant infrastructure from sharp edges that may form on the expandingsleeve distal end (130) during installation.

As seen in FIGS. 19-20, in another embodiment the sleeve retainer (200)may have a retainer flange (220) having a retainer flange overhang (222)and a retainer flange thickness (224), which while illustrated at thesleeve proximal end (120) in FIGS. 19-20 could also be located at thesleeve distal end (130) as seen in FIG. 48. When positioned at thesleeve proximal end (120), the retainer flange overhang (222) helps sealboth the internal structure of the workpieces and the blind fastenerfrom the natural elements. Additionally, the retainer flange thickness(224) is sufficient to form a water tight gasket when the blind fasteneris actuated to a locked state.

As seen in FIGS. 21-22, one embodiment may incorporate a single sleeveretainer (200). Alternatively, the embodiment of FIGS. 21-22 may alsoincorporate a sleeve distal end (130) sleeve retainer (200), such asthat seen in FIG. 48, or the sleeve distal end (130) shroud (300) asillustrated in FIGS. 21-22. Further, the embodiment of FIGS. 19-20 mayincorporate a sleeve proximal end (120) sleeve retainer (200), eitherwith or without a retainer flange (200), in unison with a sleeve distalend (130) sleeve retainer (200), such as that seen in FIG. 48, or thesleeve distal end (130) shroud (300) as illustrated in FIGS. 19-20. Evenfurther, in the embodiments of FIGS. 36-41, a single sleeve retainer(200) may encircle majority, or all, of the sleeve (100), as will beexplained in greater detail later, which may be used alone or incombination with any of the disclosed sleeve retainer (200) and/orshroud (300) embodiments.

In some embodiments, seen in FIGS. 36-41, a sleeve retainer (200) may bemade of a contractible material, which may be incorporated individuallyinto the blind fastener or may be applied in addition to at least oneother sleeve retainer (200). In this embodiment the sleeve retainer(200) has a sleeve engagement section (210), as seen in FIGS. 36 and 38,which cooperates with the retainer engagement region (160) aftercontraction to maintain the sleeve (100) in an initial state. Theretainer engagement region (160) may be recessed as illustrated in FIGS.19, 20, 21 and 48. Alternatively, the retainer engagement region (160)may be on a non-recessed sleeve (100) retainer engagement region (160),as illustrated in FIGS. 40, 41 and 42, which may simply be the exteriorsurface of the sleeve (100). In one contractible material sleeveretainer (200) embodiment the sleeve retainer (200) has a sleeveengagement section length (212) prior to contraction that is at least25% of the retainer engagement region length (164), which means that inone embodiment the sleeve engagement section length (212) prior tocontraction is at least 25% of the overall sleeve length (155). In afurther contractible material sleeve retainer (200) embodiment thesleeve retainer (200) has a sleeve engagement section length (212) priorto contraction that is at least 50% of the retainer engagement regionlength (164), which means that in one embodiment the sleeve engagementsection length (212) prior to contraction is at least 50% of the overallsleeve length (155). In yet another contractible material sleeveretainer (200) embodiment the sleeve retainer (200) has a sleeveengagement section length (212) prior to contraction that is at least75% of the retainer engagement region length (164), which means that inone embodiment the sleeve engagement section length (212) prior tocontraction is at least 75% of the overall sleeve length (155). While aneven further contractible material sleeve retainer (200) embodiment hasa sleeve engagement section length (212) prior to contraction that is atleast 100% of the retainer engagement region length (164), which meansthat in one embodiment the sleeve engagement section length (212) priorto contraction is at least 100% of the overall sleeve length (155).Another embodiment is designed to encircle the entire sleeve length(155) post-contraction of the sleeve retainer (200), and therefore has asleeve engagement section length (212) prior to contraction that is atleast 110% of the retainer engagement region length (164), which meansthat in one embodiment the sleeve engagement section length (212) priorto contraction is at least 110% of the overall sleeve length (155), andthus at least partially wraps either the sleeve proximal end (120), thesleeve distal end (130), or both, upon contraction.

Such contractible material sleeve retainer (200) embodiments have apre-contraction inner and outer sleeve engagement section diameter (214,216), as seen in FIG. 42. Furthermore, the pre-contraction sleeveengagement section inner diameter (214) is at least 5% larger than thesleeve retainer engagement region diameter (168). During assembly thesleeve (100) is positioned inside the sleeve retainer (200), as seen inFIGS. 37 and 38, which may include the use of a temporary mandrel toposition the sleeve (100), or the sleeve (100) may already be positionedon a tensioning section (450) of the expander (400). Then a sleeveretainer (200) contraction activation means (H) is applied to the sleeveretainer (200). The contraction activation means (H) may include, but isnot limited to, heat activation and/or dehydration activation. Forinstance, in one embodiment, a heat activated sleeve retainer (200) maybe a shrink wrap sleeve that may be made of, but is not limited to,PETG, PVC, OPS, PE, or PLA shrink films. In another embodiment, thatuses dehydration activation, the sleeve retainer (200) may be a shrinkwrap sleeve made of, but not limited to, gelatin and collagen materials.

In other embodiments that have shrink wrap covering 100% of the sleeve(100) outer surface, the shrink wrap sleeve retainer (200) presents aseamless outer surface thereby further reducing the likelihood ofsnagging any of the components of the blind fastener as it is installed.Additionally, the shrink wrap sleeve, or any portion of the sleeveretainer (200), may be printed with installation instructions andwarnings for the end user, and may be color coded to easily inform theuser of an attribute of the blind fastener. For instance in oneembodiment the color of the contractible material sleeve retainer (200)is indicative of the length of the blind fastener, or the thickness ofthe workpiece joint that may be joined via the blind fastener; whereasin another embodiment the color is indicative of the diameter of theblind fastener, or the size of the opening in the workpieces that may bejoined via the blind fastener.

Furthermore, in some embodiments the sleeve retainer (200) ensures thecomponents of the sleeve (100) and expander (400) remain together duringshipping and installation, which improves worksite safety, particularlywhen the blind fastener is in the process of being installed high abovethe ground. After the sleeve retainer (200) has been fully contractedthe sleeve engagement section inner diameter (214) is approximately thesame as the retainer engagement region diameter (168) wherein the sleeveretainer engagement section (210) is in physical contact with theretainer engagement region (160) and imparts a radially compressive loadon the sleeve (100). In yet another embodiment the contractible sleeveretainer (200) covers a portion of the sleeve (100), a portion of theexpander (400), and a portion of the nut (500); while in a furtherembodiment it also covers a washer system (600) located between the nut(500) and the sleeve (100) thereby holding all of the components of theblind fastener together in a predetermined relationship.

With reference to FIGS. 36-41, in one embodiment the fully contractedsleeve retainer (200) is provided on the retainer engagement region(160) located on the sleeve proximal end (120) and extends from thesleeve proximal end (120) towards the sleeve distal end (130). Inanother embodiment, the contracted sleeve engagement section length(212) is at least 25% of the sleeve length (155). In another embodiment,the contracted sleeve engagement section length (212) is at least 50% ofthe sleeve length (155). In yet another embodiment, the contractedsleeve engagement section length (212) is at least 75% of the sleevelength (155). In one embodiment, the fully contracted sleeve retainer(200) is provided on the retainer engagement region (160) located on thesleeve distal end (130) and extends from the sleeve distal end (130)towards the sleeve proximal end (120). In another embodiment, thecontracted sleeve engagement section length (212) is at least 25% of thesleeve length (155). In yet another embodiment, the contracted sleeveengagement section length (212) is at least 50% of the sleeve length(155). In still another embodiment, the contracted sleeve engagementsection length (212) is at least 75% of the sleeve length (155). Inother embodiments the sleeve retainer (200) and retainer engagementregion (160) maybe offset from the sleeve proximal end (120) or thesleeve distal end (130). In another embodiment, the sleeve retainer andretainer engagement region (160) maybe located at the sleeve length(155) midpoint, as seen in FIGS. 21 and 22. In yet another embodiment,the sleeve (100) may have at least two sleeve retainers (200). In oneembodiment the sleeve (100) may be provided with two retainer engagementregions (160) and two sleeve retainers (200), having one retainerengagement region (160) and one sleeve retainer (200) located on thesleeve proximal end (120) and the other retainer engagement region (160)and sleeve retainer (200) located on the sleeve distal end (130).Alternatively, in another embodiment, the sleeve (100) may be providedwith two retainer engagement regions (160) and sleeve retainers (200),having one retainer engagement region (160) and one sleeve retainer(200) located on the sleeve proximal end (120) or sleeve distal end(130) and the other retainer engagement region (160) and sleeve retainer(200) located on the sleeve length (155) midpoint. In yet anotherembodiment, the fully contracted sleeve retainer (200) fully encompassesand engages the retainer engagement region (160) wherein the retainerengagement region length (164) is substantially equal to the sleevelength (155).

The use of sleeve retainer (200) made of a contractible materialinstalled, or shrunk, around at least a portion of the sleeve (100)after the sleeve (100) is positioned on the expander (400) offersseveral advantages. The compressive radial force exerted by thecontractible sleeve retainer (200) forces the sleeve (100) against theexpander (400) and keeps it in place. For example in FIG. 29 thecontractible sleeve retainer (200) is applied after the sleeve (100) ispositioned on the tensioning section (450) of the expander (400), whicheffectively locks the sleeve (100) on the tensioning section (450)because the sleeve inner diameter (150) is less than the expansionsection diameter (442).

Referring again to FIGS. 36-41, the contractible sleeve retainer (200)may be sized to extend beyond an end, or both ends, of the sleeve (100),and thereby also engage a portion of the expander (400). In oneembodiment the contractible sleeve retainer (200) is specifically sizedto extend beyond one or both ends of the sleeve (100) and engage theexpander (400) at each end of the sleeve (100). This is particularlybeneficial in a further embodiment in which the blind fastener includesfactory installed thread lubricant, often referred to as anti-seize orbolt lubricant. Thread lubricant is often essential to achieve thenecessary tension in blind fasteners used in structural connections. Forexample, looking at the embodiment of FIGS. 26-28, a thread lubricantmay be applied to a portion of the tensioning section (450), the sleeve(100) may be positioned over the thread lubricant, and then thecontractible sleeve retainer (200) may be applied to cover the assembly.The thread lubricant may include compositions of oil, grease, wax,graphite, and/or molybdenum disulfide. In one embodiment the threadlubricant includes a solid lubricant in a paste formulation to provide aconsistent coefficient of friction and a paste that does not evaporateand is resistant to washout. Such solid lubricants include, but are notlimited to, MoS₂, white solids, graphite, copper, zirconium dioxide, andPTFE. In one paste embodiment the base oil is a glycol, and in an evenfurther embodiment the paste includes a polyalkylene glycol base oil.The contractible sleeve retainer (200) retains the thread lubricant andis constructed of an oil resistant material that does not break-downwhen it is in contact with the thread lubricant, and thereby preventsthe thread lubricant from coming in contact with the installer's hands,which is very beneficial considering that these blind fasteners areoften installed several hundred feet above the ground. Additionally, inanother embodiment the expander (400) incorporates an anti-frictioncoating to provide a dry lubrication that does not attract dirt and dustsuch as a dry film lubricant spray. In a further embodiment at least aportion of the nut (500) includes an anti-friction coating, which in oneembodiment is applied to the side of the nut (500) in contact with thewasher system (600). In another embodiment at least a portion of thewasher system (600) includes an anti-friction coating, which in oneembodiment is applied to the portion of the washer system (600) that isin contact with the nut (500).

Alternatively, at least a portion of the sleeve retainer (200) may beelastic, which may include a sleeve retainer (200) having quasi-rubberband qualities and characteristics. In fact, the sleeve retainer (200)may be made of natural rubber, synthetic rubbers including, but notlimited to, nitrile and butyl rubbers, and polymers. An elastic sleeveretainer (200) allows the sleeve engagement section (210) to stretchover the retainer engagement region (160), and also allows the sleeve(100) to expand when the expander (400) is drawn into the sleeve (100).Further, an elastic sleeve retainer (200) may be sized to remain intension when cooperating with the retainer engagement region (160) tosecurely hold the two or more sleeve sections firmly in an alignedinitial state, as seen in FIGS. 6 and 8.

Regardless of the type of sleeve retainer (200), the initial state ofthe sleeve (100), and the associated properties, are defined when thesleeve (100) is on the tensioning section (450) of the expander (400),as seen in FIG. 29, and in cross-section in FIG. 6. In some embodimentsa multi-section sleeve (100) is assembled and then slid onto thetensioning section (450), while in other embodiments the multi-sectionsleeve (100) may be assembled on the tensioning section (450) and ineffect using the expander (400) to aid in the assembly of themulti-section sleeve (100) until the sleeve retainer (200), or sleeveretainers (200), and/or shroud (300) are in position and keep the sleeve(100) in an assembled state. Regardless, at least one point along thesleeve length (155) has the sleeve inner diameter (150) in the initialstate less than the maximum expansion section diameter (442), therebypreventing the majority of the sleeve (100) from coming in contact withthe expansion section (440) until the blind fastener is in use, althoughas seen in FIG. 29 a portion of the sleeve throat (180), seen in FIG.20, may extend beyond the expansion section transition (444) withoutresulting in an increase in the sleeve outer diameter (140).

In the multi-section sleeve (100) embodiment of FIGS. 6 & 8, the edgesof each sleeve section (101, 102, 103, 104) are in contact with theedges of the adjacent sleeve sections in the initial state, and a smallgap is illustrated between the sleeve inner diameter (150) and theexpansion section diameter (442). Thus, in this embodiment the sleeveretainer (200) and/or shroud (300) is applying a radial compressiveforce on the sleeve sections (101, 102, 103, 104) and maintaining theiredges in contact, however in this position there is no radialcompressive force transferred from the sleeve (100) to the expander(400) because the edges of the sleeve sections (101, 102, 103, 104)contact each other. However, one skilled in the art will appreciate thatthe sleeve sections (101, 102, 103, 104) may be sized so that the edgesdo not contact one another when positioned about the expansion section(440), and therefore the radial compressive force may be transferredfrom the sleeve (100) to the expander (400). In fact, in one embodimentthe radial compressive force is large enough to overcome gravity andkeep the sleeve (100) from sliding off the expander (400), even in theorientation of FIG. 29, rotated 180 degrees; and in one embodiment theradial compressive force is at least 1 lbf, while in a furtherembodiment it is at least 2.5 lbf, and in yet another embodiment it isat least 5 lbf. The sleeve (100) also has an expanded state whichdefines the characteristics of the sleeve (100) when a portion of theexpansion section (440) of the expander (400) has been drawn into thestructural region (170) of the sleeve (100) and expanding at least aportion of the structural region (170) of the sleeve (100) from theinitial state to this expanded state. Further, as a portion of thelocking section (430) is drawn past the sleeve distal end (130) towardthe sleeve proximal end (120), it expands, or deforms, at least aportion of the sleeve distal end (130) to a locked state, as seen inFIGS. 13 and 15.

In the embodiments in which at least one point along the sleeve length(155) has the sleeve inner diameter (150) in the initial state less thanthe maximum expansion section diameter (442), thereby preventing themajority of the sleeve (100) from coming in contact with the expansionsection (440) until the blind fastener is in use, one benefit is the toease of installation of the blind fastener into the first and secondworkpiece openings (722, 822). Furthermore, the sleeve retainer (200)may be located on and overlap the sleeve distal end (130) therebyforming a sleeve retainer protrusion (230). The sleeve retainerprotrusion has a sleeve retainer protrusion length (232) and a sleeveretainer protrusion width (234), as seen in FIG. 48. The retainerprotrusion width (234) may have the same thickness as the fullycontracted sleeve retainer (200). Alternatively, in one embodiment, theretainer protrusion width (234) may have a thickness that is at least10-50% greater than the sleeve retainer (200) sleeve engagement sectionouter diameter (216) minus the sleeve engagement section inner diameter(214). In another embodiment, the retainer protrusion width (234) mayhave a thickness that is at least 15% to 30% greater than the sleeveretainer (200) sleeve engagement section outer diameter (216) minus thesleeve engagement section inner diameter (214). The sleeve retainerprotrusion (230) provides the benefit of aiding in the alignment andinstallation of the blind protective fastener and also helps shieldwires, cables and other important infrastructure from sharp edges thatmay form on the expanding sleeve distal end (130) during installation.The sleeve retainer (200) may cooperate with the sleeve proximal end(120), as seen in FIGS. 19 and 20, or may be located at other locationsthroughout the length of sleeve (100). One advantage of the sleeveretainer (200) located on the sleeve proximal end (120) is that itallows for a greater surface area of the structural region (170) to bein contact with the walls of the first and second workpiece openings(722, 822) and does not run the risk of aligning with the workpieceinterface (900) which would create an elastic void in the shear plane.Further, in another embodiment the shroud (300), located at the oppositeend of the blind fastener, may also be elastic and stretch over theshroud engagement region (190), and also allows the sleeve (100) toexpand when the expander (400) is drawn into the sleeve (100). Further,the shroud (300) may be sized to remain in tension when cooperating withthe shroud engagement region (190) to securely hold the two or moresleeve sections firmly in an aligned initial state, as seen in FIGS. 6and 8. Thus, the sleeve retainer (200) may exert a retainer force on thesleeve (100), and if present, the shroud (300) may exert a shroud forceon the sleeve (100). In one embodiment a first retainer force is appliedto the sleeve proximal end (120) and a second retainer force is appliedto the sleeve distal end (130); and the second retainer force is ±20% ofthe first retainer force to present a relatively balanced load on thesleeve (100). In yet a further embodiment these elements and theirassociated forces are located at opposite ends of the sleeve (100) andthey are designed so that retainer force is ±50% of the shroud force,while in another embodiment the retainer force is ±25% of the shroudforce, and in an even further embodiment the retainer force is ±10% ofthe shroud force. Such balanced compressive loading of the sleeve (100)ensures the individual sections of the sleeve (100) remain in thedesired position in the initial state and simplify the assembly process.

In yet another embodiment, the sleeve retainer (200) may be made of anon-elastic non-contractible material such as, but not limited to, anon-elastic plastic or metal band, having a sleeve engagement section(210), which slips around, or is wrapped around, the retainer engagementarea (160); wherein the retainer engagement region diameter (168) isapproximately the same as the sleeve retainers (200) sleeve engagementsection inner diameter (214). Furthermore, the sleeve retainer (200) maybe further secured to the sleeve (100) by a layer of adhesive locatedbetween the retainer engagement area (160) and the sleeve engagementsection (210).

Now turning to the expander (400), as seen in FIGS. 17, 18, 25, and 26,it has an expander proximal end (410), an expander distal end (420), atensioning section (450), a locking section (430), and an expansionsection (440) between the tensioning section (450) and the lockingsection (430). The tensioning section (450) has a tensioning sectiondiameter (452) and a tensioning section length (454). Additionally, thelocking section (430) has a locking section diameter (432), and theexpansion section (440) has an expansion section diameter (442) and anexpansion section transition (444), as illustrated in FIG. 17. In someembodiments the tensioning section (450) may include a tensioningsection gripping region (456), which may be an external surface as seenin FIG. 17, or an internal socket as seen in FIG. 18.

All of the disclosed relationships herein, including the lengths,angles, diameters, thicknesses, strength, elongation, and hardness,among the various portions of the expander (400) and the variousportions of the sleeve (100), play an important role in the ease ofinstallation and performance of the blind bolt, particularly when theblind fastener must be installed with a preload of at least 70,000 lbf.As previously touched upon one application of the blind fastener is intower construction, and specifically in wind turbine tower construction.In such applications the tower is structural steel, and therefore thebolting in the tower splices must come under the Research Council onStructural Connections. This is the North American body that writes thedesign and installation specifications which govern all boltedstructural steel connections. The only way to ensure that the bolts aregoing to survive in service is to get them uniformly tightened, readtensioned or loaded, to a very high percentage of their strength, whichis the best insurance against loosening because the correctly tensionedbolts will not see very much change in tension as the external serviceloads vary. Correctly tensioned fasteners only experience a smallpercentage change in tension as external loads vary and therefore havean extremely long, practically infinite, fatigue life. However, if thefasteners are not tensioned correctly they will experience a largepercentage change in tension, cyclically, and their residual clampingforce will gradually diminish. Once the clamping force has droppedsignificantly, every cycle of external load will change the force in thefastener by a very high percentage, and the fatigue life of the fastenerwill limit its serviceability. Unlike many fasteners, the present blindfastener is specifically designed to encourage proper tensioning of theexpander (400) and radial expansion of the sleeve (100) to engage theworkpieces (700, 800), while still improving upon the ease ofinstallation and incorporating protective features. In one particularlyeffective embodiment the expansion section diameter (442) is at least7.5% greater than the tensioning section diameter (452), and the lockingsection diameter (432) is at least 15% greater than the expansionsection diameter (442), while the structural region (170) has astructural region wall thickness (172) that is less than a differencebetween the locking section diameter (432) and the tensioning sectiondiameter (452). While the previous embodiment includes a minimumrelationship between the expansion section diameter (442) and thetensioning section diameter (452), as well as the locking sectiondiameter (432) and the expansion section diameter (442), anotherembodiment recognizes preferred performance in a range with an upperboundary. In this embodiment the expansion section diameter (442) is nomore than 15% greater than the tensioning section diameter (452); whilein an even further embodiment the locking section diameter (432) is nomore than 30% greater than the expansion section diameter (442), therebyproviding a blind fastener that does not require drastically oversizedworkpiece openings (720, 820) and improves shear load distribution tothe blind fastener at the workpiece interface (900).

With reference to FIGS. 17, 18, and 20, the locking section (430) has alocking section transition length (436) and a locking section transitionangle (435), the expansion section (440) has an expansion sectiontransition length (446) and an expansion section transition angle (445),and the structural region (170) of the sleeve (100) has a structuralregion length (174). The relationships of these lengths and anglespromotes preferred loading of the expander (400) to achieve thenecessary preload, as well as expansion of sleeve (100) to engage theworkpieces (700, 800). In one such embodiment the locking sectiontransition length (436) is at least twice the expansion sectiontransition length (446), and the expansion section length (448) is atleast 25% of the structural region length (174).

In a further embodiment the expansion section length (448) is 25-75% ofthe structural region length (174), further providing great flexibilityfor the blind fastener and assuring a solid plane of the sleeve (100)and the expansion section (440) at the workpiece interface (900). Asseen in FIG. 20, the sleeve distal end (130) has a sleeve throat (180)having a throat length (182) and a throat angle (184). In one embodimentthe throat angle (184) is 5-50 degrees, and the throat angle (184) isless than the expansion section transition angle (445), seen in FIG. 18,thereby providing a rather distinct point of expansion of the sleeve(100), which allows for gradual loading of the expander (400) as theexpansion section transition (444) wedges the sleeve (100) radiallyagainst the workpieces (700, 800) as the expander (400) is drawn intothe sleeve (100). Additionally, this virtually immediate engagement ofthe interior of the sleeve (100) with the expansion section (440),within five rotations of the nut (500) around the tensioning section(450), and the associated engagement of the exterior of the sleeve (100)with the workpieces (700, 800) allows the blind fastener to be installedwith a single tool rotating the nut (500), without the need for a secondspecialized tool to hold the sleeve (100) and/or expander (400) andprevent them from rotating. While the sleeve (100) and/or expander (400)may rotate initially for five seconds or less, by the time the nut (500)has rotated around the tensioning section (450) five times the sleeve(100) will have engaged the workpieces (700, 800) and the expansionsection (440) will have engaged the sleeve (100) such that sleeve (100)and the fastener (400) no longer rotate.

In another embodiment the relationships of these lengths and anglesachieve engagement within three rotations of the nut (500) around thetensioning section (450) in a time period of less than two seconds. In afurther embodiment embracing the initial rapid radial expansion of thesleeve (100) over the expansion section transition (444) and latergradual deformation of the sleeve distal end (130) by the lockingsection transition (434) and final loading of the expander (400), thelocking section transition angle (435) is less than 50% of the expansionsection transition angle (445). In an even further embodiment the throatangle (184) is greater than locking section transition angle (435);while in another embodiment the throat angle (184) is at least 5 degreesless than the expansion section transition angle (445), and the throatangle (184) is no more than 15 degrees greater than locking sectiontransition angle (435). This preferential loading is exhibited inanother embodiment in which the throat length (182) is greater than theexpansion section transition length (446), and the locking sectiontransition length (436) is greater than the expansion section transitionlength (446). In one particular embodiment the length of the expander(400) from the expander proximal end (410) to the expander distal end(420) is at least 100 mm, while in another embodiment it is at least 150mm, and is at least 200 mm in a further embodiment. Additionally, in oneembodiment of the blind fastener the tensioning section diameter (452)is at least 0.75″, while in another embodiment it is at least 1.25″, andis at least 2.0″ in a further embodiment. Such long lengths and largediameters require unique relationships to ensure ease of installation,engagement of the sleeve (100), and the ability to achieve the necessarytension in the expander (400); relationships that are largely irrelevantto conventional length and diameter blind bolt assemblies. The surfaceof the locking section transition (434) may include a friction enhancingsurface pattern to reduce the likelihood of the sleeve (100) andexpander (400) rotating with respect to one another once the lockingsection transition (434) has engaged the sleeve (100). In one suchembodiment the surface pattern is a friction promoting stipplingpattern, whereas in another embodiment it includes a series oflongitudinal channels.

Further, in one embodiment the tensioning section diameter (452) is 75to 95% the diameter of the expansion section (440). The tensioningsection (450) may utilize a threaded system, shown in FIGS. 17, 18, 23and 25, to actuate the expander (400) while putting the blind fastenerin a locked state by rotational forces applied to either the nut (500),or in some embodiments the tensioning section gripping region (456).Testing has shown that an advantage of the present invention is that atensioning section gripping region (456) is not actually required toprevent the expander (400) from rotating as the nut (500) is turned todraw the expander (400) into the sleeve (100). The tight fit of theexpander (400) and the edges of the sleeve (100) cooperate to preventthe expander (400) from rotating as the nut (500) rotates and draws theexpander (400) into the sleeve (100). In one particular embodiment atleast a portion of the expander (400) is composed of material having aRockwell B-Scale hardness that is at least 10 units higher than theRockwell B-Scale hardness of the sleeve (100), while in a furtherembodiment the Rockwell B-Scale hardness differential is at least 15units, and in an even further embodiment the Rockwell B-Scale hardnessdifferential is at least 20 units. In even further embodiments thetensioning section gripping region (456) may be in the form of bolthead, as seen in FIGS. 23 and 24, or recessed in the expander proximalend (410), as seen in FIG. 18.

The expansion section (440) serves the purpose of expanding the sleeve(100) so that the sleeve outside diameter (140) is approximately thesame as the first workpiece opening diameter (722) and second workpieceopening diameter (822), as illustrated in FIGS. 9-11, while exerting asubstantial radial load on the openings (720, 820). In one embodiment,the pre-installed sleeve inner diameter (150) is 3 to 20% smaller thanthe expansion section diameter (442). In another embodiment, thepre-installed sleeve inner diameter (150) is 5 to 15% smaller than theexpansion section diameter (442). In yet another embodiment, theexpansion section diameter (442) is 5 to 20% smaller than the lockingsection diameter (432). In another embodiment the expansion sectiondiameter (442) is 7.5 to 15% smaller than the locking section diameter(432). However, in an alternative set of embodiments the pre-installedsleeve inner diameter (150) is approximately equal to, or larger than,the expansion section diameter (442); thus in a further embodiment thepre-installed sleeve inner diameter (150) is 0.1 to 10% larger than theexpansion section diameter (442), while in another embodiment it is 1 to5% larger than the expansion section diameter (442), and in an evenfurther embodiment it is 2.5 to 5% larger than the expansion sectiondiameter (442).

In order to ensure proper alignment and ingress of the expander (400),the expansion section (440) has an expansion section transition (444),as seen in FIG. 18, having an expansion section transition angle (445)and expansion section transition length (446). In combination, thesection transition angle (445) and expansion section transition length(446) form a ramp that engages the sleeve throat (180), thereby feedingthe expansion section (440) into the sleeve (100) when the protectiveblind faster is actuated. Furthermore, in one embodiment the expansionsection transition angle (445) is 5-50 degrees, while in a furtherembodiment the expansion section transition angle (445) is 10-45degrees, and in an even further embodiment the expansion sectiontransition angle (445) is 15-30 degrees. In one embodiment the expansionsection transition angle (445) is equal to the throat angle (184). Afurther variation incorporates an expansion section transition angle(445) that is at least 1 degree greater than the throat angle (184), butpreferably less than 5 degrees greater than the throat angle (184).

The locking section diameter (432) may be 5-25% larger than expansionsection diameter (442), but the locking section diameter (432) may beequal to, or less than the sleeve outer diameter (140). In anotherembodiment, the locking section diameter (432) is 1-10% smaller than thesleeve outer diameter (140). These unique relationships of the diametersensure that the components of the blind fastener are compactlyconfigured for installation, yet the expansion section (440) serves toexpand the sleeve (100) so that the sleeve (100) and the expansionsection (440) completely fill the first workpiece opening (720) andsecond workpiece opening (820) to create a solid metal shear plane atthe workpiece interface (900).

Furthermore, the locking section (430) has an overall locking sectionlength (438) that includes a locking section transition (434) that has alocking section transition angle (435) and a locking section transitionlength (436), as illustrated in FIGS. 17 and 18. In combination, thelocking section transition angle (435) and a locking section transitionlength (436) form a ramp that engages the sleeve proximal end (120) anddeforms the sleeve (100), thereby locking the blind fastener into place.In another embodiment, the locking section (430) includes a plurality ofindividual ramps, each having their own the locking section transitionangle (435) and a locking section transition length (436), as seen inFIG. 25. In one embodiment the locking section transition angle (435) is5-50 degrees, while in a further embodiment the locking sectiontransition angle (435) is 10-45 degrees, and in an even furtherembodiment the locking section transition angle (435) is 15-30 degrees.In one embodiment the locking section transition angle (435) is equal tothe throat angle (184). A further variation incorporates a lockingsection transition angle (435) that is at least 1 degree greater thanthe throat angle (184), but preferably less than 5 degrees greater thanthe throat angle (184).

Furthermore, in one embodiment, the locking section diameter (432), seenin FIG. 17, is 0-5% smaller than the sleeve (100) retainer engagementregion diameter (168), seen in FIG. 20. In another embodiment, thelocking section diameter (432) is 1-20% larger than the sleeve (100)retainer engagement region diameter (168). In yet another embodiment,the locking section diameter (432) is 5-15% larger than the sleeve (100)retainer engagement region diameter (168).

In an alternative embodiment of the blind fastener, the expander (400)is composed of a tensioning section (450) that is separate and distinctfrom an expansion section (440), as seen in FIGS. 23 and 24. In thisembodiment, tensioning section (450) engages threads in a bore locatedin the part composed of the expansion section (440) and locking section(430). As the tensioning section (450) is actuated, the part composed ofthe expansion section (440) and locking section (430) is drawn into thesleeve (100), thereby locking the blind protective fastener into place.

Referring back to FIG. 17, one particular embodiment has an expansionsection diameter (442) that is 7.5-15% greater than the tensioningsection diameter (452), and a locking section diameter (432) that is15-30% greater than the expansion section diameter (442). In a furtherembodiment the locking section transition length (436) is at least twicethe expansion section transition length (446), and the expansion sectionlength (448) is at least 25% of the structural region length (174). Inyet a further embodiment the expansion section length (448) is 25-75% ofthe structural region length (174). Another embodiment incorporates alocking section transition length (436) that is greater than the shroudengagement region length (192). These relationships provide preferredradial and longitudinal loading of the sleeve (100), while facilitatingsmooth ingress of the expander (400) into the sleeve (100) and preferreddeflection of the sleeve distal end (130) for secure locking of theworkpieces.

In one embodiment, seen in FIG. 26, the expander (400) includes a regionof expander indicia (460) that is discernable by a person, such as aninspector or foreman, analyzing the installed blind fastener usingbinoculars from a distance of at least 100 yards. The expander indicia(460) easily informs a user of an attribute of the blind fastener. Forinstance in one embodiment the expander indicia (460) is a color codedregion on the expander (400). In one embodiment the color of theexpander (400) is indicative of the length of the blind fastener, or thethickness of the workpiece joint that may be joined via the blindfastener; whereas in another embodiment the color is indicative of thediameter of the blind fastener, or the size of the opening in theworkpieces that may be joined via the blind fastener. For example, inone embodiment the expander indicia (460) is indicative of the allowablejoint thickness to be joined via a specific blind fastener, and theindicia (460) is visible from long distances. Thus, an inspector wouldbe able to remain on the ground consulting the blueprints of a new towerand then look up at the constructed tower and identify whether the blindfastener identified on the plans was indeed the one used inconstruction. In one embodiment the expander indicia (460) covers atleast 25% of the exposed surface area of the tensioning section (450),located external to the workpieces (700, 800) and nut (500); while in afurther embodiment the expander indicia (460) covers at least 50% of theexposed surface area; and in yet a further embodiment the expanderindicia (460) covers at 1.0 square inch of the tensioning section (450).In one embodiment the color coded expander indicia (460) alsocorresponds with the color coding of the sleeve retainer (200), therebycreating a system in which the installer can easily identify the properblind fastener for a particular locations and install it, and then theinspector can easily verify from a distance that the proper blindfastener was indeed installed.

Additionally, as seen in FIG. 51, the externally exposed portion of theexpander (400) may serve many important functions. For instance, thetensioning section (450), which is generally threaded, may provide anextra inch or more of available real estate along the exposed portion ofthe tensioning section (450) to attach any number of accessories,including, but not limited to, an anchor (1000), or an attachment device(1100), such as the illustrated step. Such anchors (1000) areparticularly important during the construction of a tower and provideworkers with virtually limitless locations to tie-off their safetylines. Additionally the anchors (1000) may be used with suspensionequipment such as a suspended hoist work platform, lift, or bosun'schair. Further, this blind fastener design's extra inch or more ofavailable real estate along the exposed portion of the tensioningsection (450) provides great flexibility for later reinforcing of thetower, for instance as the technology of wind generators advances andnecessitate the tower to support greater loads.

In one particular embodiment the blind fastener has a sleeve (100)having a sleeve proximal end (120), a sleeve distal end (130), a sleeveouter diameter (140), a sleeve inner diameter (150), a retainerengagement region (160), and a structural region (170), as seen in FIGS.19 and 20. Additionally, the blind fastener has a sleeve retainer (200)having a sleeve engagement section (210) that cooperates with theretainer engagement region (160) to maintain the sleeve (100) in aninitial state. In addition to the sleeve retainer (200), the blindfastener has an expander (400) having an expander proximal end (410), anexpander distal end (420), a tensioning section (450), a locking section(430), and an expansion section (440) between the tensioning section(450) and the locking section (430), wherein the expansion section (440)has an expansion section diameter (442) and an expansion sectiontransition (444), as seen in FIG. 17, and at least one point along thelength of the sleeve (100) has the sleeve inner diameter (150) in theinitial state less than the maximum expansion section diameter (442).Furthermore, the blind fastener may have a shroud (300) that cooperateswith a portion of the sleeve (100) and encloses at least a portion ofthe expander (400) and a portion of the sleeve (100), as seen in FIGS.5, 7, 9, 11, 13 and 15. The blind fastener has a nut (500) wherein aportion of the expander (400) passes through the sleeve (100) tocooperate with the nut (500) so that relative rotation of the expander(400) and nut (500) draws the expander distal end (420) toward thesleeve proximal end (120), thereby drawing a portion of the expansionsection (440) of the expander (400) into the structural region (170) ofthe sleeve (100), as seen in FIG. 11, and expanding at least a portionof the structural region (170) of the sleeve (100) from the initialstate to an expanded state, as seen in FIG. 12. This also draws aportion of the locking section (430) past the sleeve distal end (130)toward the sleeve proximal end (120) and expands at least a portion ofthe sleeve distal end (130) to a locked state whereby the sleeve distalend (130) has been deformed to the point that it is larger than theopening in the workpieces and therefore cannot be withdrawn, as seenbest in FIG. 15. In some embodiments a shroud (300), or a portion of asleeve distal end (120) sleeve retainer (200) as seen in FIG. 48,encloses a portion of the sleeve (100) in the locked state as seen inFIGS. 13 and 15. Thus, the shroud (300), or sleeve distal end (120)sleeve retainer (200), must accommodate both the radial expansion fromthe initial state to the expanded state as the expansion section (440)forces the sleeve (100) outward and into contact with the workpieces, aswell as accommodate the change in shape of the sleeve distal end (130)as the locking section (430) bends the sleeve distal end (130) outward.

In one embodiment the blind fastener's minimum sleeve inner diameter(150) increases at least 2.5% from the initial state to the expandedstate to fill both the first and second workpiece openings (722, 822).The expanding sleeve serves to eliminate any movement in the workpiecesin relation to one another due to loose fitting fasteners; reduces thelikelihood of fasteners failings due to shear loading on the fastener;and allows the blind fastener to lock into place. As seen in FIGS. 9,10, and 11, the blind fastener has expanded so that the shear plane,located at the workpiece interface (900), is effectively completelyfilled with the structural material of the sleeve (100) and expansionsection (440). Further, the blind fastener has forced the firstworkpiece (700) and the second workpiece (800) together to reduce thelikelihood of any voids in this high stress area. The ability to haveradial expansion of the sleeve (100) from the initial state to theexpanded state ensures that workers will not oversize the openings inthe workpieces, as is often the case, which leads to loose joints,misalignment, and shear plane problems. Another embodiment provides evenfurther flexibility by having the blind fastener's minimum sleeve innerdiameter (150) increase at least 3.5% from the initial state to theexpanded state to fill both the first and second workpiece openings(722, 822); while an even further embodiment has found a preferentialrange of expansion of minimum sleeve inner diameter (150) to be 2.5-5%from the initial state to the expanded state.

In the embodiment of FIG. 5, the blind fastener has been inserted intothe workpieces but has not yet been actuated, meaning the expansionsection (440) of the expander (400) has not yet been drawn into thesleeve (100), as shown in FIG. 7. Therefore, in one embodiment, as seenin FIG. 8, at least a portion of the edges of each sleeve section (101,102, 103, 104) are in contact with the edges of the adjacent sleevesections in the initial state, and a portion of any, or all, of thesleeve sections (101, 102, 103, 104) may be in contact with a portion ofthe tensioning section (450) of the expander (400). In fact, in oneembodiment at least 50% of the surface area of the edges of each sleevesection (101, 102, 103, 104) are in contact with the adjacent sleevesection's edge, and at least a portion of abutting edges aresubstantially parallel. In a further embodiment, in the unactuatedstate, the interior surface of each sleeve section is in contact withthe exterior surface of the threads of the tensioning section (450)throughout at least 50% of the sleeve length (155). In yet anotherembodiment illustrated in FIGS. 6 and 8, 100% of the surface area of theedges of each sleeve section (101, 102, 103, 104) are in contact withthe adjacent sleeve section's edge, and at least a portion of abuttingedges are substantially parallel in the unactuated state, and theinterior surface of each sleeve section is in contact with the exteriorsurface of the threads of the tensioning section (450) throughout atleast 75% of the sleeve length (155). FIGS. 9-12 illustrate the changesto FIGS. 5-8 when the blind fastener is partially-actuated, meaning thatthe expansion section (440) has entered the sleeve (100) and resulted inradial expansion of the sleeve (100). Further, FIGS. 13-16 illustratethe changes to FIGS. 5-12 when the blind fastener is fully-actuated,meaning that at least a portion of the locking section (430) has enteredthe sleeve (100) and resulted in further radial expansion of at least aportion of the sleeve throat (180). In series of figures of just onepossible embodiment since the radius of curvature of the interiorsurface of the sleeve sections (101, 102, 103, 104) is within 5% of theradius of curvature of the exterior surface of the tensioning section(450), a small gap between the inner surface of the sleeve sections(101, 102, 103, 104) and the exterior surface of the expansion section(440) appears in the partially-actuated state seen in FIG. 12 until thesleeve sections (101, 102, 103, 104) are slightly bent as the tensileload is further applied to the blind fastener and the fully-actuatedstate is reached, as seen in FIG. 16, and there is complete surfacecontact between the inner surface of the sleeve sections (101, 102, 103,104) and the exterior surface of the expansion section (440), as well asthe exterior surface of the sleeve sections (101, 102, 103, 104) and theinterior surface of the workpieces (700, 800). This deformation of thesleeve (100) allows the blind fastener system to compensate for anyirregularities in the workpiece openings (720, 820).

However, such deformation changes the loading profile of the blindfastener and may be undesirable in embodiments having greater sleevethicknesses and material strength. Thus, in another embodiment, shown inthe series of FIGS. 57-59, which is analogous to FIGS. 8, 12, and 16 ofthe previously discussed embodiment, wherein FIG. 57 is thecross-section in which the blind fastener has been inserted into theworkpieces but has not yet been actuated, meaning the expansion section(440) of the expander (400) has not yet been drawn into the sleeve(100), as shown in FIG. 7; while FIG. 58 is the cross-section in whichthe blind fastener is partially-actuated, meaning that the expansionsection (440) has entered the sleeve (100) and resulted in radialexpansion of the sleeve (100); and FIG. 59 is the cross-section in whichthe blind fastener is fully-actuated, meaning that at least a portion ofthe locking section (430) has entered the sleeve (100) and resulted infurther radial expansion of at least a portion of the sleeve throat(180). In this embodiment the sleeve (100) is designed to have apredetermined desired curvature when full-actuated without any bendingor deformation of the sleeve (100), or individual sleeve sections (101,102, 103, 104). Thus, as seen in FIG. 59, in one embodiment the interiorsurface of the sleeve (100), or one or more of the sleeve sections (101,102, 103, 104), has a sleeve radius of curvature (Rs), and the exteriorsurface of the expansion section (440) has an expansion section radiusof curvature (Res). In one particular embodiment each of the one or moresleeve sections has a sleeve radius of curvature (Rs) that is ±5% of theexpansion section radius of curvature (Res) throughout at least 25% ofthe structural region length (174); while in a further embodimentmajority of the sleeve sections have a sleeve radius of curvature (Rs)that is ±5% of the expansion section radius of curvature (Res)throughout at least 50% of the structural region length (174); while inan even further embodiment all of the sleeve sections have a sleeveradius of curvature (Rs) that is ±5% of the expansion section radius ofcurvature (Res) throughout at least 75% of the structural region length(174).

In a further embodiment each of the one or more sleeve sections has asleeve radius of curvature (Rs) that is ±2.5% of the expansion sectionradius of curvature (Res) throughout at least 25% of the structuralregion length (174); while in a further embodiment majority of thesleeve sections have a sleeve radius of curvature (Rs) that is ±2.5% ofthe expansion section radius of curvature (Res) throughout at least 50%of the structural region length (174); while in an even furtherembodiment all of the sleeve sections have a sleeve radius of curvature(Rs) that is ±2.5% of the expansion section radius of curvature (Res)throughout at least 75% of the structural region length (174). In aneven further embodiment each of the one or more sleeve sections has asleeve radius of curvature (Rs) that is equal to the expansion sectionradius of curvature (Res) throughout at least 25% of the structuralregion length (174); while in a further embodiment majority of thesleeve sections have a sleeve radius of curvature (Rs) that is equal tothe expansion section radius of curvature (Res) throughout at least 50%of the structural region length (174); while in an even furtherembodiment all of the sleeve sections have a sleeve radius of curvature(Rs) that is equal to the expansion section radius of curvature (Res)throughout at least 75% of the structural region length (174).Additionally, in the fully-actuated state of FIG. 59, with each sleevesection in contact with the expansion section (440), there is a sectiongap (106) between the adjacent sidewalls of the individual sleevesections. Specifically, in the four sleeve section embodiment of FIG.59, the first sleeve section (101) has two first sleeve sectionsidewalls (101 a), likewise the second sleeve section (102) has twosecond sleeve section sidewalls (102 a), the third sleeve section (103)has two third sleeve section sidewalls (103 a), and the fourth sleevesection (104) has two fourth sleeve section sidewalls (104 a). Thesection gap (106) is the minimum distance between the adjacent sectionsidewalls. In one particular embodiment effective loading and shearresistance is achieved when each section gap (106) is less than themaximum structural region wall thickness (172); while in a furtherembodiment each section gap (106) is less than 50% of the maximumstructural region wall thickness (172); while in an even furtherembodiment each section gap (106) is 10-50% of the maximum structuralregion wall thickness (172); and in a still further embodiment eachsection gap (106) is 20-40% of the maximum structural region wallthickness (172). In one embodiment the maximum structural region wallthickness (172) is 2-10 mm, and each section gap (106) is less than 6mm; while in a further embodiment the maximum structural region wallthickness (172) is 2-6 mm, and each section gap (106) is no more than 4mm; while in a further embodiment the maximum structural region wallthickness (172) is 3-5 mm, and each section gap (106) is no more than 3mm, and no more than 2 mm in an even further embodiment. The curvatureand size of each sleeve section are designed to provide a compact sizewhen in the un-actuated state, as seen in FIG. 57, to achieve thedisclosed relationships that allows for reduced size opening in theworkpieces while ensuring easy installation of the blind fastener. Inanother embodiment the sleeve length (155) is 30-120 mm, the structuralregion length (174) is 20-100 mm, the tensioning section length (454) is60-145 mm, the expansion section length (448) is 25-75 mm, thetensioning section diameter (452) 12-30 mm, the expansion sectiondiameter (442) is 15-35 mm, the locking section diameter (432) is 20-40mm; while in a further embodiment the structural region length (174) is25-60 mm, the tensioning section length (454) is 80-120 mm, theexpansion section length (448) is 35-65 mm, the tensioning sectiondiameter (452) 15-25 mm, the expansion section diameter (442) is 20-30mm, the locking section diameter (432) is 25-35 mm.

In the multi-section sleeve (100) embodiment of FIGS. 6 & 8, the edgesof each sleeve section (101, 102, 103, 104) are in contact with theedges of the adjacent sleeve sections in the initial state, and a smallgap is illustrated between the sleeve inner diameter (150) and theexpansion section diameter (442). Thus, in this embodiment the sleeveretainer (200) and/or shroud (300) is applying a radial compressiveforce on the sleeve sections (101, 102, 103, 104) and maintaining theiredges in contact, however in this position there is no radialcompressive force transferred from the sleeve (100) to the expander(400) because the edges of the sleeve sections (101, 102, 103, 104)contact each other. However, one skilled in the art will appreciate thatthe sleeve sections (101, 102, 103, 104) may be sized so that the edgesdo not contact one another when positioned about the expansion section(440), and therefore the radial compressive force may be transferredfrom the sleeve (100) to the expander (400).

In another embodiment the sleeve retainer (200) and/or the shroud (300)are adhesively attached to the sleeve (100) to further ensure thedesired positioning, and in the case of the shroud (300), so that theexpander (400) cannot simply slide out of the sleeve (100), even whenoriented vertically without the nut (500) in place, thereby offeringgreat safety advantages during installations in which the workpieceopenings are high above the ground. Thus, in one embodiment the shroud(300) will retain and confine the expander (400) even when the shroud(300) is subjected to a force of at least 2 lbf along the longitudinalaxis of the expander (400), which ensures that the shroud (300) willsupport the weight of the expander (400) when oriented verticallywithout the nut (500) in place. In an even further embodiment the shroud(300) will retain and confine the expander (400) even when the shroud(300) is subjected to a force of at least 5 lbf along the longitudinalaxis of the expander (400), which ensures that the shroud (300) willretain the expander (400) without the nut (500) in place even if forceis applied to the expander (400) during installation.

In a further embodiment of the blind fastener, the sleeve retainer (200)cooperates with the sleeve proximal end (120) and further includes aretainer flange (220) extending radially beyond the maximum sleeve outerdiameter (140) in the initial state by a retainer flange overhang (222),as seen in FIGS. 19 and 20, and is at least 10% of the maximum sleeveouter diameter (140) in the initial state, and at least 25% of sleeveengagement section length (212). The retainer flange overhang (222)creates a weather-tight seal and provides stability to the sleeve (100).In another embodiment the retainer flange (220) has a longitudinalretainer flange thickness (224), as seen in FIG. 20, that is at least25% of sleeve engagement section length (212) ensuring adequate materialis present to create a good seal when exposed to the loads common withsuch blind fasteners. Additionally, the inner diameter of the retainerflange (220), through which the expander (400) passes, may be sized sothat it is less than the sleeve inner diameter (150) in the initialstate, as can be imagined in FIGS. 19 and 20, so that a portion of theretainer flange (220) engages the tensioning section (450). One benefitof this embodiment is that the retainer flange (220) effectively gripsthe tensioning section (450) and keeps the sleeve (100) in place duringtransport and initial installation.

In another embodiment the retainer engagement region (160) has aretainer engagement region wall thickness (162), and the structuralregion (170) has a structural region wall thickness (172), as seen inFIG. 20. In this embodiment, the minimum retainer engagement region wallthickness (162) is at least 25% of the maximum structural region wallthickness (172) to ensure the retainer engagement region (160) does notcompress longitudinally as the expansion section (440) of the expander(400) is drawn into the structural region (170) of the sleeve (100). Ina further embodiment the minimum the retainer engagement region wallthickness (162) is 25-50% of the maximum structural region wallthickness (172). In yet another embodiment the retainer engagementregion (160) is a circumferential recess in the exterior surface of thesleeve (100) thereby creating at least one retainer engagement regionledge (166) to shield at least one edge of the sleeve retainer (200). Inyet another embodiment, the retainer engagement region ledge (166) has aledge width that is 25-50% of the maximum structural region wallthickness (172).

In one embodiment the shroud (300), and/or the sleeve retainer (200), iswaterproof. In an even further embodiment, either, or both, the shroud(300) and sleeve retainer (200) have at least a portion composed ofthermoplastic polyurethane, natural rubber, urethane, neoprene, nitrile,butyl, EPDM, styrene butadiene, silicone, hypalon, or viton. In anotherembodiment at least a portion of the shroud (300), and/or the sleeveretainer (200), is composed of material having a tensile strength of atleast 1000 psi, an elongation % of at least 150%, a tear-strength of atleast 500-1000 pounds per linear inch, and a service temperature ratingof at least 150 degrees Fahrenheit. In an even further embodiment atleast a portion of the shroud (300), and/or the sleeve retainer (200),is composed of material having a tensile strength of at least 4000 psiand an elongation % of at least 300%. In an even further embodiment thesleeve retainer (200) and the shroud (300) may create a substantiallysealed environment and retain a lubricant within the blind fastener, andtherefore they may be composed of elastomeric materials that areresistant to breaking down in the presence of lubricants, such asthermoplastic polyurethane, nitrile rubber, silicone, fluoro-elastomers,EPDM, and perfluoro-elastomers.

The sleeve (100) may include a shroud engagement region (190) having ashroud engagement region length (192) that is at least 10% of thestructural region length (174), and the shroud (300) cooperates with theshroud engagement region (190). In a further embodiment the shroudengagement region length (192) is 10-50% of the structural region length(174), while in an even further embodiment the shroud engagement region(190) is a circumferential recess in the exterior surface of the sleeve(100) thereby creating at least one shroud engagement region ledge (194)to shield at least one edge of the shroud (300). The shroud engagementregion (190) has a shroud engagement region wall thickness (196), andthe structural region (170) has a structural region wall thickness(172), whereby in one embodiment the minimum shroud engagement regionwall thickness (196) is at least 25% of the maximum structural regionwall thickness (172) to ensure the shroud engagement region (190) doesnot compress longitudinally as the expander (400) is drawn into thesleeve (100). Even further, the minimum shroud engagement region wallthickness (196) is 25-50% of the maximum structural region wallthickness (172) provides the necessary strength while also facilitatingbending of the sleeve (100) for locking. These relationships provide ashroud (300) to sleeve (100) connection that is strong enough towithstand the forces encountered as the sleeve (100) deforms to a lockedstate.

In the embodiments illustrated in FIGS. 3-5, 7, 9, 11, 13 and 15 theshroud (300) encloses the sleeve distal end (130) and the expanderdistal end (420) in the initial state, the expanded state, and thelocked state. Therefore in these embodiments the shroud (300) must beconstructed to accommodate the change in shape of the sleeve (100)associated with the different states. In some embodiments the shroud(300) is elastic and it stretches to continue to cover the edges of thesleeve (100) even as the edges are flared outward to the locked state,thereby ensuring any apparatus on the blind side of the workpieces isnot exposed to sharp metallic edges of the sleeve (100). In oneparticular embodiment the shroud proximal end (310) is attached to thesleeve (100) and the shroud distal end (320) totally encloses and sealsthe sleeve distal end (130). Alternatively, the shroud (300) does nothave to incorporate elastic elements. Rather the shroud (300) may beconfigured so that there is space between the shroud distal end (320)and the expander distal end (420). The space accommodates the changes inshape of the sleeve (100). One embodiment ensures that the extra spacein the shroud (300) does not result in a baggy shroud (300) that may bea hindrance as the blind fastener is fed into a blind hole. In fact, inone such embodiment the extra shroud (300) length may be folded andadhered internal to the shroud (300) so that it is not presented untilthe sleeve (100) deforms into the locked state.

The blind fastener is designed for ease of installation in a hole thatis not much larger than the blind fastener. Therefore, in one embodimentthe initial state the exterior surface of the shroud (300) does notextend radially beyond the maximum sleeve outer diameter (140).

Regardless of whether the shroud (300) is elastic or not, in oneembodiment the shroud thickness (330) is no greater than the thicknessof the sleeve engagement section (210), thereby ensuring the shroud(300) does not extend radially outward beyond the maximum sleeve outerdiameter (140) and reducing the likelihood of snagging the shroud (300)as the blind fastener is fed through the first and second workpieceopenings (722, 822).

In yet another embodiment the nut (500) cannot be removed from theexpander (400). This may be accomplished in a number of methodsincluding, but not limited to, striking the expander proximal end (410)after the nut (500) is in place to slightly enlarge the proximal end sothat the nut (500) cannot pass over the enlarged end, placing a spotweld adjacent the expander proximal end (410) after the nut (500) is inplace so that the nut (500) cannot pass over the weld material, and/orattaching a blocking member to the expander proximal end (410) after thenut (500) is in place so that the nut (500) cannot pass over theblocking member.

Some embodiments incorporate a washer system (600), which may consist ofone or more washers. One such embodiment is a hardened washer and aself-indicating direct tension indicator. The illustrated embodimentsshow a three washer system (600) having a self-indicating direct tensionindicator between two hardened washers.

In one embodiment the sleeve (100) has an ultimate tensile strength thatis within ±50% of the ultimate tensile strength of the expander (400),while in a further embodiment the sleeve (100) has an ultimate tensilestrength that is within ±25% of the ultimate tensile strength of theexpander (400). Still further, in another embodiment the ultimatetensile strength of at least one of the expander (400) or sleeve (100)is at least 800 MPa, while in a further embodiment the ultimate tensilestrength at least one of the expander (400) and the sleeve (100) is atleast 100 MPa less than the other component. In a further embodiment theexpander (400) has an ultimate tensile strength that is at least 25%greater than the ultimate tensile strength of the sleeve (100); while ina further embodiment it is at least 35% greater. In one embodiment theultimate tensile strength of the expander (400) is at least 800 MPa,while the ultimate tensile strength of the sleeve (100) is less than 650MPa; while in yet another embodiment the ultimate tensile strength ofthe expander (400) is at least 1000 MPa and the ultimate tensilestrength of the sleeve (100) is less than 550 MPa. Still further, inanother embodiment the Brinell Hardness (Tungsten Carbide Ball 3000 KG)of the expander (400) is greater than that of the sleeve (100); in fact,in a further embodiment the Brinell Hardness (Tungsten Carbide Ball 3000KG) of the expander (400) is at least 10% greater than that of thesleeve (100), and, in another embodiment, is at least 25% greater thanthat of the sleeve (100). In yet another embodiment the percentelongation to break of the expander (400) is at least 30% less than thatof the sleeve (100); and in an even further embodiment the percentelongation to break of the expander (400) is at least 50% less than thatof the sleeve (100) while still having a elongation to break of theexpander (400) that is at least 8 percent. These unique relationshipsbetween the properties of the sleeve (100) and the expander (400)facilitate the preferred deformation and loading of the components toachieve the required tensioning of the expander (400) in structuraltower installations where an inspector must verify that the expander(400) has been tensioned to at least 70 kips.

As seen in FIGS. 52-54, the expander (400) may have a removable expanderportion (470). In one embodiment the removable expander portion (470) isa portion of the tensioning section (450). In one particular embodimenta length of the removable expander portion (470) is at least 25% of thetensioning section length (454), while in a further embodiment thelength of the removable expander portion (470) is at least 40% of thetensioning section length (454), and in a further embodiment the lengthof the removable expander portion (470) is at least 50% of thetensioning section length (454). The removable expander portion (470)may be joined to the expander (400) in any number of ways, however theillustrated embodiment incorporates cooperating male and female sectionshaving threads opposite of those on the exterior surface of thetensioning section (450), which when joined cooperates with the bolt(500). The removable expander portion (470) may be removed afterinstallation to reduce the amount of the expander (400) that extendsbeyond the bolt (500). In one embodiment the removable expander portion(470) is composed of a different material than the rest of the expander(400). In fact in one embodiment the removable expander portion (470)has an ultimate tensile strength that is at least 100 MPa less than thatof the expansion section (440); and in a further embodiment theremovable expander portion (470) has an ultimate tensile strength thatis at least 200 MPa less than that of the expansion section (440). Theremovable expander portion (470) may be composed of a material having adensity that is at least 25% less than the density of the expansionsection (440); while in a further embodiment the density of theremovable expander portion (470) is at least 50% less that the densityof the expansion section (440). In yet a further embodiment theremovable expander portion (470) is composed of non-metallic material,which in one embodiment is a polymeric material. For example, theremovable expander portion (470) may be composed of magnesium alloys,aluminum/aluminum alloys, titanium alloys, carbon steels, stainlesssteels, PH (precipitation-hardenable) alloys, copper alloys, and nickelalloys, just to name a few. Non-metallic embodiments may be composed ofmaterials such as a polycaprolactam, a polyhexamethylene adipinamide, ora copolymer of hexamethylene diamine adipic acid and caprolactam,however other embodiments may include polypropylene (PP), nylon 6(polyamide 6), polybutylene terephthalates (PBT), thermoplasticpolyurethane (TPU), PC/ABS alloy, PPS, PEEK, and semi-crystallineengineering resin systems, some of which may be fiber reinforced.

Numerous alterations, modifications, and variations of the embodimentsdisclosed herein will be apparent to those skilled in the art and theyare all anticipated and contemplated to be within the spirit and scopeof the instant invention. For example, although specific embodimentshave been described in detail, those with skill in the art willunderstand that the preceding embodiments and variations can be modifiedto incorporate various types of substitute and or additional oralternative materials, relative arrangement of elements, and dimensionalconfigurations. Accordingly, even though only few variations of thepresent invention are described herein, it is to be understood that thepractice of such additional modifications and variations and theequivalents thereof, are within the spirit and scope of the invention asdefined in the following claims.

We claim:
 1. A blind fastener, comprising: a sleeve (100) having asleeve proximal end (120), a sleeve distal end (130), a sleeve length(155), a sleeve outer diameter (140), a sleeve inner diameter (150), anda structural region (170) having a structural region wall thickness(172) and a structural region length (174); an expander (400) having alocking section (430), a constant diameter expansion section (440), anexpander distal end (420), and a bore, wherein the expansion section(440) has a constant expansion section diameter (442), a taperedexpansion section transition (444), and an expansion section length(448) is at least 25% of the structural region length (174), wherein thelocking section (430) has a locking section diameter (432) that is atleast 15% greater than the expansion section diameter (442), and aportion of the sleeve (100) has the sleeve inner diameter (150), in aninitial state, less than the maximum expansion section diameter (442); atensioning section (450) separate and distinct from the expander (400)and configured to mechanically cooperate with the expander (400),wherein an end of the tensioning section (450) is configured as atensioning section gripping region (456), the tensioning section (450)has a tensioning section diameter (452), the expansion section diameter(442) is at least 7.5% greater than the tensioning section diameter(452), and the structural region wall thickness (172) that is less thana difference between the locking section diameter (432) and thetensioning section diameter (452); and wherein a portion of thetensioning section (450) passes through the sleeve (100) to cooperatewith the expander (400) so that relative rotation of the tensioningsection (450) and the expander (400): (i) draws the expander distal end(420) toward the sleeve proximal end (120); (ii) thereby drawing aportion of the expansion section (440) of the expander (400) into thestructural region (170) of the sleeve (100) and expanding at least aportion of the structural region (170) of the sleeve (100) from theinitial state to an expanded state; and (iii) thereby drawing a portionof the locking section (430) past the sleeve distal end (130) toward thesleeve proximal end (120) and deforming at least a portion of the sleevedistal end (130) to a locked state.
 2. The blind fastener of claim 1,wherein the tensioning section gripping region (456) is configured as abolt head.
 3. The blind fastener of claim 1, wherein the expansionsection diameter is no more than 15% greater than the tensioning sectiondiameter.
 4. The blind fastener of claim 3, wherein the locking sectiondiameter (432) is no more than 30% greater than the expansion sectiondiameter (442).
 5. The blind fastener of claim 1, wherein the lockingsection (430) has a locking section transition length (436) and alocking section transition angle (435), the expansion section (440) hasan expansion section transition length (446) and an expansion sectiontransition angle (445), and the structural region (170) of the sleeve(100) has a structural region length (174), wherein the locking sectiontransition length (436) is at least twice the expansion sectiontransition length (446).
 6. The blind fastener of claim 5, wherein theexpansion section length (448) is 25-75% of the structural region length(174).
 7. The blind fastener of claim 6, wherein the sleeve distal end(130) has a sleeve throat (180) having a throat length (182) and athroat angle (184), wherein the throat angle (184) is 5-50 degrees, andthe throat angle (184) is less than the expansion section transitionangle (445).
 8. The blind fastener of claim 7, wherein the lockingsection transition angle (435) is less than 50% of the expansion sectiontransition angle (445).
 9. The blind fastener of claim 7, wherein thethroat angle (184) is greater than locking section transition angle(435).
 10. The blind fastener of claim 9, wherein the throat angle (184)is at least 5 degrees less than the expansion section transition angle(445), and the throat angle (184) is no more than 15 degrees greaterthan locking section transition angle (435).
 11. The blind fastener ofclaim 7, wherein the throat length (182) is greater than the expansionsection transition length (446), and the locking section transitionlength (436) is greater than the expansion section transition length(446).
 12. The blind fastener of claim 1, wherein the sleeve (100)includes at least two distinct and separate sections (101, 102).
 13. Theblind fastener of claim 12, further including a sleeve retainer (200)having a sleeve engagement section (210) that cooperates with a retainerengagement region (160) in the sleeve (100) to maintain the at least twodistinct sections (101, 102) in a predetermined relationship.
 14. Theblind fastener of claim 13, wherein at least a portion of the sleeveretainer (200) is elastic and the sleeve retainer (200) exerts acompressive force on the sleeve (100).
 15. The blind fastener of claim14, wherein a portion of the sleeve retainer (200) is in tension whencooperating with the retainer engagement region (160) and the sleeve(100) is located around the tensioning section (450).
 16. The blindfastener of claim 13, wherein the sleeve retainer (200) is contractiblewhen activated.
 17. The blind fastener of claim 13, wherein the sleeveengagement section (210) has a sleeve engagement section length (212), asleeve engagement section inner diameter (214), and a sleeve engagementsection outer diameter (216), the sleeve engagement section (210) wrapscircumferentially around the sleeve (100), the structural region (170)of the sleeve (100) has a structural region length (174), the retainerengagement region (160) has a retainer engagement region length (164),and both the retainer engagement region length (164) and the sleeveengagement section length (212) are at least 10% of the structuralregion length (174).
 18. The blind fastener of claim 17, wherein thesleeve retainer (200) extends beyond the sleeve distal end (130) forminga sleeve retainer protrusion (230) having a sleeve retainer protrusionlength (232) and a sleeve retainer protrusion width (234), wherein thesleeve retainer protrusion length (232) is at least 5% of the retainerengagement region length (164).
 19. The blind fastener of claim 13,wherein the retainer engagement region (160) has a retainer engagementregion wall thickness (162), and the structural region (170) has astructural region wall thickness (172), whereby the minimum retainerengagement region wall thickness (162) is at least 25% of the maximumstructural region wall thickness (172) to ensure the retainer engagementregion (160) does not compress longitudinally as the expansion section(440) of the expander (400) is drawn into the structural region (170) ofthe sleeve (100).
 20. The blind fastener of claim 19, wherein theretainer engagement region (160) is a circumferential recess in theexterior surface of the sleeve (100) thereby creating at least oneretainer engagement region ledge (166) to shield at least one edge ofthe sleeve retainer (200).
 21. A blind fastener, comprising: a sleeve(100) having a sleeve proximal end (120), a sleeve distal end (130), asleeve length (155), a sleeve outer diameter (140), a sleeve innerdiameter (150), and a structural region (170) having a structural regionlength (174), wherein the sleeve distal end (130) has a sleeve throat(180) having a throat length (182) and a throat angle (184) that is 5-50degrees; an expander (400) having a locking section (430), an expansionsection (440), an expander distal end (420), and a bore, wherein theexpansion section (440) has an expansion section diameter (442) and anexpansion section transition (444), and a portion of the sleeve (100)has the sleeve inner diameter (150), in an initial state, less than themaximum expansion section diameter (442), wherein: (i) the lockingsection (430) has a locking section transition length (436) and alocking section transition angle (435), and the expansion section (440)has an expansion section transition length (446) and an expansionsection transition angle (445), wherein the locking section transitionlength (436) is at least twice the expansion section transition length(446), the expansion section length (448) is 25-75% of the structuralregion length (174), and the throat angle (184) is less than theexpansion section transition angle (445); a tensioning section (450)separate and distinct from the expander (400) and configured tomechanically cooperate with the expander (400), wherein an end of thetensioning section (450) is configured as a tensioning section grippingregion (456); and wherein a portion of the tensioning section (450)passes through the sleeve (100) to cooperate with the expander (400) sothat relative rotation of the tensioning section (450) and the expander(400): (i) draws the expander distal end (420) toward the sleeveproximal end (120); (ii) thereby drawing a portion of the expansionsection (440) of the expander (400) into the structural region (170) ofthe sleeve (100) and expanding at least a portion of the structuralregion (170) of the sleeve (100) from the initial state to an expandedstate; and (iii) thereby drawing a portion of the locking section (430)past the sleeve distal end (130) toward the sleeve proximal end (120)and deforming at least a portion of the sleeve distal end (130) to alocked state.
 22. A blind fastener, comprising: a sleeve (100) having asleeve proximal end (120), a sleeve distal end (130), a sleeve length(155), a sleeve outer diameter (140), a sleeve inner diameter (150), aretainer engagement region (160) having a retainer engagement regionwall thickness (162) and formed as a circumferential recess in anexterior sleeve surface and creating at least one retainer engagementregion ledge (166), and a structural region (170) having a structuralregion wall thickness (172), wherein the sleeve (100) includes at leasttwo distinct and separate sections (101, 102); a sleeve retainer (200)having a sleeve engagement section (210) that cooperates with thecircumferential recess of the retainer engagement region (160) tomaintain the at least two distinct sections (101, 102) in apredetermined relationship, and the at least one retainer engagementregion ledge (166) shields at least one edge of the sleeve retainer(200); an expander (400) having a locking section (430), an expansionsection (440), an expander distal end (420), and a bore, wherein theexpansion section (440) has an expansion section diameter (442) and anexpansion section transition (444), and a portion of the sleeve (100)has the sleeve inner diameter (150), in an initial state, less than themaximum expansion section diameter (442); a tensioning section (450)separate and distinct from the expander (400) and configured tomechanically cooperate with the expander (400), wherein an end of thetensioning section (450) is configured as a tensioning section grippingregion (456); and wherein a portion of the tensioning section (450)passes through the sleeve (100) to cooperate with the expander (400) sothat relative rotation of the tensioning section (450) and the expander(400): (i) draws the expander distal end (420) toward the sleeveproximal end (120); (ii) thereby drawing a portion of the expansionsection (440) of the expander (400) into the structural region (170) ofthe sleeve (100) and expanding at least a portion of the structuralregion (170) of the sleeve (100) from the initial state to an expandedstate; (iii) thereby drawing a portion of the locking section (430) pastthe sleeve distal end (130) toward the sleeve proximal end (120) anddeforming at least a portion of the sleeve distal end (130) to a lockedstate; and (iv) the minimum retainer engagement region wall thickness(162) is at least 25% of the maximum structural region wall thickness(172) to ensure the retainer engagement region (160) does not compresslongitudinally as the expansion section (440) of the expander (400) isdrawn into the structural region (170) of the sleeve (100).
 23. Theblind fastener of claim 22, wherein the locking section (430) has alocking section diameter (432), and the tensioning section (450) has atensioning section diameter (452), wherein the expansion sectiondiameter (442) is at least 7.5% greater than the tensioning sectiondiameter (452), and the locking section diameter (432) is at least 15%greater than the expansion section diameter (442), and wherein thestructural region (170) has a structural region wall thickness (172)that is less than a difference between the locking section diameter(432) and the tensioning section diameter (452).